二叉树的深度最小的

 

class Solution {
public:
    int run(TreeNode *root) {
        
        if (root == NULL){
            return 0;
            
        }
        if (root->left == NULL){
            
            return run(root->right) + 1;
        }
        if (root->right == NULL){
            return run(root->left) + 1;
            
        }
        
        int l = run(root->left);
        int r = run(root->right);
        
        return l > r ? (r + 1) : (l + 1);
    }
    
};